diff --git a/NEWS.md b/NEWS.md
index 474ccbb3..f2649de4 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -11,6 +11,7 @@
 -   `WeibSurvOS` now does not return an error for large values of t.
 -   `PWCSurvOS` now does not return an error for large values of t. It also no longer returns values larger than 1. It is significantly faster, based on a closed form calculation instead of numerical integration.
 -   `getSimulatedData` now also works when there are no transitions from progression to death, similarly for `getOneClinicalTrial` (which now warns if there are no such transitions at all).
+-   `corPFSOS` now undoes the `future` plan upon function exit.
 
 ### Miscellaneous
 
diff --git a/R/corPFSOS.R b/R/corPFSOS.R
index 25e16974..38d71320 100644
--- a/R/corPFSOS.R
+++ b/R/corPFSOS.R
@@ -314,7 +314,8 @@ corPFSOS <- function(data, transition, bootstrap = TRUE, bootstrap_n = 100, conf
   trans <- estimateParams(data, transition)
   res <- list("corPFSOS" = corTrans(trans))
   if (bootstrap) {
-    future::plan(future::multisession, workers = max(1, parallelly::availableCores() - 1))
+    oplan <- future::plan(future::multisession, workers = parallelly::availableCores(omit = 1))
+    on.exit(future::plan(oplan), add = TRUE)
     ids <- lapply(1:bootstrap_n, function(x) sample(seq_len(nrow(data)), nrow(data), replace = TRUE))
     corBootstrap <- furrr::future_map_dbl(ids, ~ {
       furrr::furrr_options(